Optical imaging has evolved to become a useful diagnostic tool. Various system designs have been developed to accommodate imaging of various parts of the human body. For example, Hillman et al. (Phys. Med. Biol, 46 (2001)1117-1130) describes an arrangement for acquiring optical signals from a forearm; and Pogue et al. (Opt. Express 1 (1997) 391-403) describes a system for breast imaging. Optical imaging systems have also been developed for small mammals with a view of providing a research tool that can image changes in the physiology of the mammals and that can also provide information on the biodistribution molecules such as chromophores and fluorophores. An example of an optical imaging system for small mammals has been described in patent application WO 0137195.
Diagnosis as well as physiological and pharmacokinetics studies rely on time course protocols to reveal temporal changes within a subject with respect to predetermined characteristics. Thus, a suitable imaging tool should be able to reliably and reproducibly produce images of the same region of interest in a subject over time. In this respect accurate and reproducible positioning of the subject relative to the imaging optics is very important.
While the above mentioned optical imaging systems permit the repositioning of a subject in more or less the same position over several imaging sessions, they lack a positioning system that is reliable and precise. Thus there is a need for improved systems and methods for selecting regions of interest in a subject and reproducibly image the selected regions over time.